Top 12 Voip Engineer Skills to Put on Your Resume

In today's fast-shifting telecom world, a sharp VoIP skill set isn’t optional. It’s ballast and booster. Put the right capabilities on your resume and you don’t just look prepared—you look indispensable.

VoIP Engineer Skills

1. SIP
2. RTP
3. Asterisk
4. Cisco Unified Communications
5. VoIP Security
6. QoS
7. Wireshark
8. FreeSWITCH
9. Avaya Systems
10. Session Border Controllers
11. MPLS
12. PBX Systems

1. SIP

SIP (Session Initiation Protocol) is the signaling backbone that starts, modifies, and ends voice, video, and messaging sessions across IP networks.

Why It's Important

Without SIP, sessions don’t ring, roam, or end cleanly. It coordinates people, endpoints, and policies—so real-time conversations actually happen and scale.

How to Improve SIP Skills

1. Design the network for voice: Separate and prioritize signaling from media. Mark DSCP appropriately (CS3/AF31 for SIP, EF for RTP). Keep latency, jitter, and loss on a short leash.

2. Harden signaling: Use TLS for SIP, authenticate every endpoint, rate-limit registrations and INVITEs, turn on topology hiding, and anchor through an SBC. No open proxies. Ever.

3. NAT traversal that actually works: Favor PJSIP with proper contact/record-route handling. Use ICE/STUN/TURN when remote or mobile clients wander outside the LAN.

4. Simplify codecs and reduce transcoding: Standardize on a small set (Opus, G.711; add G.729 only if licensing and bandwidth require). Fewer conversions, fewer surprises.

5. Observe the call flows: Capture and read SIP ladders. Look for retransmits, 4xx/5xx patterns, and early media quirks. Build alerts around registration storms and failure spikes.

6. Keep current: Prefer PJSIP over legacy chan_sip. Patch regularly. Validate certificates and ciphers. Test failover paths, not just on paper.

How to Display SIP Skills on Your Resume

2. RTP

RTP (Real-time Transport Protocol) carries the media—voice and video—fast and in order, while RTCP watches quality and timing.

Why It's Important

If SIP is the handshake, RTP is the conversation. Low delay, steady timing, minimal loss. Otherwise words turn to mush.

How to Improve RTP Skills

1. Tune for the clock: Target one-way latency under ~150 ms, jitter under ~30 ms, and packet loss under ~1%. Packetization at 20 ms is a safe default; don’t oversize packets on shaky links.

2. Jitter buffers that adapt: Enable dynamic jitter buffering on endpoints and servers. Watch RTCP reports and trim or extend buffers based on reality, not guesses.

3. Mark and queue correctly: DSCP EF for RTP. Map to strict-priority queues. Keep WRED away from voice. Shape downstream links so bursts don’t crush the conversation.

4. Secure the stream: SRTP for media, with keys from SIP/TLS (SDES) or DTLS-SRTP. Verify cipher suites. No cleartext across untrusted paths.

5. Control bandwidth smartly: Pick efficient codecs for WAN (Opus shines), avoid gratuitous transcoding, and size links for peak concurrency, not averages.

6. Watch the metrics: Trend jitter, loss, MOS, and burst density. Correlate RTP issues with specific subnets, devices, or times of day to pinpoint root causes.

How to Display RTP Skills on Your Resume

3. Asterisk

Asterisk is the open-source engine for building PBX features, IVRs, call control, and custom voice apps.

Why It's Important

It bends to your dial plan. Integrates with almost anything. And it’s field-tested at scale from labs to large contact centers.

How to Improve Asterisk Skills

1. Prefer PJSIP: Use pjsip.conf instead of legacy sip.conf. Cleaner configuration, better NAT handling, richer features.

2. Dialplan discipline: Keep contexts tight. Normalize numbers early. Use macros/Gosub for reuse. Log call decisions so debugging isn’t a scavenger hunt.

3. Limit transcoding: It’s CPU-hungry. Standardize codecs end-to-end where possible. If you must transcode, size the server and measure.

4. Secure the edges: TLS/SRTP, permit/deny ACLs, strong auth, fail2ban, and sane transport ports. Separate management interfaces from voice planes.

5. Observe and test: Turn on PJSIP logging when needed, rotate logs, monitor channel counts, queue stats, and thread usage. Load-test before rollout.

6. Automate: Use AMI/ARI for external control, provisioning, and real-time orchestration. Version-control configs. Bake golden images.

How to Display Asterisk Skills on Your Resume

4. Cisco Unified Communications

Cisco UC brings CUCM, CUBE, Unity, Expressway, and endpoints under one roof—on-prem, hybrid, or cloud-backed.

Why It's Important

Enterprise dialing plans, secure trunks, mobile and remote access, survivability—designed to keep conversations flowing even when the network hiccups.

How to Improve Cisco Unified Communications Skills

1. Get the dial plan right: Normalize early, route predictably, and document every translation. CAC where it matters. SRST for branch survival.

2. Harden and encrypt: SIP TLS and SRTP everywhere possible, secure phones with certificates, and lock admin roles to least privilege.

3. Edge with CUBE: Do SIP normalization, media anchoring, and interop at the border. Monitor sessions, licenses, and DSP utilization.

4. Remote work that feels local: Use Expressway MRA or approved remote solutions. Validate ICE/TURN paths for soft clients and mobile devices.

5. Stay current: Keep firmware and SU levels aligned, manage certificates before they expire, and check smart licensing health regularly.

How to Display Cisco Unified Communications Skills on Your Resume

5. VoIP Security

VoIP security defends signaling, media, credentials, and billing from prying eyes and greedy hands.

Why It's Important

Eavesdropping, toll fraud, denial of service—small slips become costly outages. Security keeps the lights on and the ledgers clean.

How to Improve VoIP Security Skills

1. Encrypt end to end: TLS for SIP. SRTP for media. Strong ciphers only. Pin certificates and rotate them on schedule.

2. Lock down identity: Unique credentials per device, MFA for admin portals, IP-based access controls, and just-enough privileges for operators.

3. Protect the border: SBCs for topology hiding, rate limits, SIP sanity checks, fraud rules, and geo blocks. Kill the SIP ALG on edge firewalls.

4. Watch the money: Cap destinations, set per-user call limits, alert on unusual ACD/ASR shifts and out-of-hours spikes. Disable costly countries unless needed.

5. Segment and observe: Isolate voice VLANs, separate management networks, and stream logs to a SIEM. Regular penetration tests, regular patching.

6. Regulatory ready: For the U.S., ensure E911 compliance (Kari’s Law, RAY BAUM’s Act) and keep location info accurate for all endpoints, including softphones.

How to Display VoIP Security Skills on Your Resume

6. QoS

QoS prioritizes voice so it doesn’t drown in a flood of best-effort traffic.

Why It's Important

Voice is picky. Delay, jitter, drops—QoS keeps those in check by giving real-time traffic the right of way.

How to Improve QoS Skills

1. Classify and mark correctly: Signaling gets CS3/AF31, RTP gets EF. Honor markings at the edge and keep them intact across the WAN.

2. Queue with intent: Strict-priority or low-latency queues for RTP, adequate bandwidth guarantees, and no WRED on voice. Shape at the egress to fit real link speeds.

3. Engineer the WAN: On MPLS or SD-WAN, map classes to provider queues that actually guarantee bandwidth and delay bounds.

4. Police wisely: Police junk traffic, shape important flows. Don’t police voice itself unless you like clipped sentences.

5. Clean up the middle: Disable SIP ALG, fix duplex mismatches, and ensure NTP clock sync so jitter buffers behave.

6. Measure relentlessly: Track jitter, loss, MOS, and queue drops per class. Tune where the evidence points, not where it’s convenient.

How to Display QoS Skills on Your Resume

7. Wireshark

Wireshark captures packets and tells the story: SIP dialogs, RTP flows, timing, errors, the lot.

Why It's Important

When calls fail or sound bad, Wireshark shows where the truth diverged—signaling logic, network timing, or endpoint behavior.

How to Improve Wireshark Skills

1. Filter like a pro: Build display filters for SIP, RTP, RTCP, by IP, by call-ID. Save them. Use color rules so issues pop at a glance.

2. Telephony views: VoIP Calls, flow sequence charts, RTP stream analysis, and the RTP Player. They speed up root cause analysis dramatically.

3. Decode what matters: Set the right dissectors, fix “Decode As” for unusual ports, and enable name resolution only when helpful.

4. See inside TLS (for labs): With a key log file, decrypt test traffic to validate SIP over TLS behavior. Keep this to controlled environments.

5. Profiles for context: Create profiles per customer or environment—custom columns (DSCP, ptime, SSRC), time display, and layout—so you’re faster every time.

How to Display Wireshark Skills on Your Resume

8. FreeSWITCH

FreeSWITCH is a flexible switching and application platform for voice, video, and messaging across protocols and codecs.

Why It's Important

It scales out, plays well with others, and exposes powerful control surfaces for custom communications.

How to Improve FreeSWITCH Skills

1. Tune core settings: Right-size threads, refine SIP timers, and optimize RTP and DB interactions. Avoid slow disk I/O—SSD helps.

2. Secure the stack: TLS/SRTP, strict auth, IP ACLs, and regular updates. Keep management modules off public interfaces.

3. Scale horizontally: Multiple instances with load balancing and clear sharding (registrations, media, apps). Plan for stateless and stateful pieces.

4. Watch everything: Centralize logs, add SIP capture, graph concurrency, CPS, and media quality. Alert on registration spikes and 5xx storms.

5. Extend cleanly: Use ESL/Event Socket, modules, and message buses for integration. Keep custom logic outside the core where possible.

How to Display FreeSWITCH Skills on Your Resume

9. Avaya Systems

Avaya solutions power enterprise telephony, contact centers, and unified communications across on-prem and cloud deployments.

Why It's Important

Many enterprises run on Avaya call control and endpoints. Interop, migrations, and daily operations demand fluency.

How to Improve Avaya Systems Skills

1. Keep platforms current: Patch cores and phones, prune weak ciphers, enforce TLS 1.2+, and manage certificates before they become fire drills.

2. Engineer SIP right: Normalize on Session Manager, anchor media when needed, and standardize codecs to cut transcoding costs.

3. Design for resiliency: Build redundancy across Communication Manager, Session Manager, and SBCs. Test failover with live traffic, not just maintenance windows.

4. Instrument the system: Use trace tools, log collectors, and quality dashboards. Follow up on user-reported call quality with real RTP evidence.

5. Harden endpoints: 802.1X where feasible, segmented voice VLANs, and locked-down admin access on phones and gateways.

How to Display Avaya Systems Skills on Your Resume

10. Session Border Controllers

SBCs sit at the edges, brokering, protecting, and normalizing SIP and media between worlds that don’t always agree.

Why It's Important

They enforce policy, cloak topology, resist attacks, and make unlike systems talk. Quietly essential.

How to Improve Session Border Controllers Skills

1. Normalize with intention: Clean headers, fix SDP, rewrite numbers, and enforce codecs so trunks interoperate without drama.

2. Anchor and secure media: SRTP/TLS, media anchoring for NAT, and ICE-lite where supported. Deter replay and downgrade attempts.

3. Protect against floods: Rate limits, SIP message sanity checks, reputation controls, and per-endpoint call caps. Alert fast on anomalies.

4. Design HA properly: Active/standby or active/active with stateful switchover. Shared IPs or DNS that actually fail over within seconds.

5. Automate certificates: Streamline CSR, issuance, and renewals. Track expiration across all interfaces and realms.

6. Measure capacity: Watch CPS, concurrent sessions, transcoding resources, and TLS offload. Scale before the cliff.

How to Display Session Border Controllers Skills on Your Resume

11. MPLS

MPLS (Multiprotocol Label Switching) moves packets by labels, not long lookups—speedy and predictable, with carrier-grade classes of service.

Why It's Important

For voice, deterministic beats lucky. MPLS gives QoS guarantees and stable paths that keep calls crisp across distances.

How to Improve MPLS Skills

1. Map classes correctly: Align EF and signaling classes to the provider’s queues that truly reserve bandwidth and low delay.

2. Engineer TE paths: Where available, steer traffic along less congested LSPs and protect with fast reroute. Avoid brownout routes for voice.

3. Assure end-to-end: Preserve DSCP edge-to-edge, verify policing policies, and shape to the real access rate so you don’t feed the dropper.

4. Plan capacity with headroom: Size for peak concurrency plus growth. Don’t forget codec, ptime, and overhead math.

5. Blend with SD-WAN wisely: If you run hybrid, ensure policy-based routing respects voice classes and fails over without jitter explosions.

How to Display MPLS Skills on Your Resume

12. PBX Systems

PBX platforms—on-prem, cloud, or hybrid—handle call routing, voicemail, conferencing, and voice apps for organizations of every size.

Why It's Important

They tie people to people. Teams to customers. And features to workflows, day after day.

How to Improve PBX Systems Skills

1. Modernize the core: Keep software current, trim legacy features you don’t need, and standardize across sites to simplify support.

2. Integrate where work happens: Connect PBX with CRM, ticketing, analytics, and collaboration tools. Click-to-call, screen pops, presence, and logging save minutes that add up.

3. Evolve the edge: Certified headsets, stable softphone builds, QoS-aware switches, and voice VLANs. Kill flaky Wi‑Fi for critical users—wire them.

4. Cloud and hybrid, carefully: Move what benefits from elasticity, keep what needs locality. Test media paths and E911 before go-live.

5. Secure the whole route: Strong auth, TLS/SRTP, role-based admin, and audit logging. Lock international dialing and premium routes by default.

6. Watch and learn: Monitor quality, capacity, and feature adoption. Train users regularly; good habits reduce tickets more than any patch.

How to Display PBX Systems Skills on Your Resume